The disclosure relates generally to magnetic resonance imaging (MRI) systems and more specifically to a thermosiphon cooling system and method for cooling superconducting magnets in MRI systems.
A superconducting magnet is used to produce a magnetic field in MRI systems. In some methods, an electric current from a power source is constantly applied to the superconducting magnet to produce the magnetic field. However, production of such a strong magnetic field entails a constant supply of the electric current in a range of hundreds of amperes. This constant supply of electric current to the superconducting magnet increases the running cost of the MRI system.
Furthermore, in certain other techniques, the superconducting magnet may be subjected to different heat loads in the MRI system. It is desirable to transfer these heat loads away from the superconducting unit to maintain the superconducting magnet at a cryogenic temperature and to operate the superconducting magnet in the superconducting state. Moreover, it is also desirable to optimally dissipate the heat from the superconducting magnet to transition the superconducting magnet from a normal state to a superconducting state without high boil-off of cryogen in the MRI system.
In a conventional system, superconducting magnets/coils are housed in a helium vessel containing about 1500 to about 2000 liters of liquid helium (He) to provide immersion cooling of the superconducting magnets/coils. Since this arrangement employs a large vessel with thousands of liters of liquid He, the arrangement is not only expensive to manufacture, but also heavy to transport and install at a desired location, such as, diagnostic centers. Additionally, the refill of thousands of liters of liquid He for delivery to remote locations may be inconvenient.
Moreover, the liquid He in these systems can sometimes boil-off during a quench event. The boiled-off helium escapes from the cryogen bath in which the magnetic coils are immersed. Thus, each quench event is followed by re-filling of the liquid He and re-ramping of the magnet, which is an expensive and time consuming event. Additionally, in conventional magnetic devices, a sophisticated exterior venting system is needed to vent the gas, such as the boiled-off He, through venting pipe stacks after the magnet and/or the switch quenches. However, the venting pipes are difficult to install. Also, in some situations, the venting of He can have environmental or regulatory concerns. Thus, conventional MRI magnet designs and their cooling arrangements can entail special installation requirements, the inability to install these systems in certain regions, and a high maintenance cost.